[lit] Add back LitTestCase

This essentially reverts a commit [1] that removed the adaptor for
Python unittests.  The code has been slightly refactored to make it more
additive: all code is contained in LitTestCase.py.

Usage sites will require a small adaption:
```
[old]
  import lit.discovery
  ...
  test_suite = lit.discovery.load_test_suite(...)

[new]
  import lit.LitTestCase
  ...
  test_suite = lit.LitTestCase.load_test_suite(...)
```

This was put back on request by Daniel Dunbar, since I wrongly assumed
that the functionality is unused.  At least llbuild still uses this [2].

[1] 70ca752ccf6a8f362aea25ccd3ee2bbceca93b20
[2] https://github.com/apple/swift-llbuild/blob/master/utils/Xcode/LitXCTestAdaptor/LitTests.py#L16

Reviewed By: ddunbar

Differential Revision: https://reviews.llvm.org/D69002

llvm-svn: 374947

3 files changed, 8 insertions, 0 deletions

diff --git a/llvm/utils/lit/tests/Inputs/unittest-adaptor/lit.cfg b/llvm/utils/lit/tests/Inputs/unittest-adaptor/lit.cfg
new file mode 100644
index 00000000000..9e08a8629a4
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/unittest-adaptor/lit.cfg
@@ -0,0 +1,6 @@
+import lit.formats
+config.name = 'unittest-adaptor'
+config.suffixes = ['.txt']
+config.test_format = lit.formats.ShTest()
+config.test_source_root = None
+config.test_exec_root = None
diff --git a/llvm/utils/lit/tests/Inputs/unittest-adaptor/test-one.txt b/llvm/utils/lit/tests/Inputs/unittest-adaptor/test-one.txt
new file mode 100644
index 00000000000..b80b60b7a27
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/unittest-adaptor/test-one.txt
@@ -0,0 +1 @@
+# RUN: true
diff --git a/llvm/utils/lit/tests/Inputs/unittest-adaptor/test-two.txt b/llvm/utils/lit/tests/Inputs/unittest-adaptor/test-two.txt
new file mode 100644
index 00000000000..49932c3006e
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/unittest-adaptor/test-two.txt
@@ -0,0 +1 @@
+# RUN: false